Expression Of PI-3K In T Lymphocytes Of Asthmatic Rat And Its Relationship With The Activation Of T Lymphocytes

ObjectiveAsthma is a kind of chronic disease caused by many kinds of inflamed cell such as lymphocyte , Eos, neutrophil,mast and some kinds of celelular component. Thus persistent chronic inflammation and hyperresponsiveness of the airway are the fundamental characteristics of asthma. T cell is thought playing a crucial role in these processes and accordingly be undertaken in recent studies of the mechanism of asthma as a warm spot.Many signal transduction pathways participated in the processes of T lymphocyte cytological effect such as differentiation, activation, proliferation, survival and anti- apoptosis. These signal transduction pathways include Ras/MAPK pathways, PLC-γpathways, PI-3K/Akt pathways, PKC/NF-κB pathways, Jak/STAT pathways, etc. And there are some crosstalks between these signal transduction pathways which enable them co-influence a series cytological effect of T cell. And different pathway lay particular emphasis on different T subtype cell.Phosphatidylinositol 3-kinase (PI-3K) is a key regulator of a variety of cellular functions from cytoskeletal organization, vesicular trafficking, and cell proliferation to apoptosis. And PI-3K/Akt signal transduction pathway one of the most important signal transduction pathway in T cell and thus has close relationships with the differentiation, the expression of activation, proliferation, survival and anti- apoptosis of T cell. It is the specific functions that it can promote the activation of T cell as a co-stimulate of CD28, regulate the expression of cyclin and cell multiplicaiton factor to maintain the regular cell cycle of T cell, rivalry P53 and Fas-induced apoptosis of T cell by regulating kinase activation associated signal transducter and the expression of apoptosis regulating factor, etc. Recent studies have showed that PI-3K/Akt signal transduction pathway has an important effect on the activation, cytokines synthesis and secretion , survival and anti- apoptosis of T subtype cell.In view of the important role Th2 cell playing in the course of asthma, we hope to invest whether PI-3K/Akt signal transduction pathway plays some role in this disease especially in T helper 2 cell or not. Thus, our study now is to explore the expression of PI-3K in T lymphocyte of asthmatic rat and the relationship between PI-3K and activation of T lymphocyte, and then make a cursory judgement on the role of PI-3K signal transduction pathway which would play in the change of cytological effect of T cell.Methods:In our experiment, we established rat asthmatic model, cultured T helper 2 cell in vitro and measured the expression of PI-3K and IL-4 in T cells and supernatants respectively by two distinctive ways. 24 Wistar rats were randomly divided into 4 groups as normal control, asthmatic group for 1 week, asthmatic group for 2 weeks and asthmatic group for 4 weeks. T lymphocyte were isolated and purified from blood of each rat and the expression of PI-3K were observed by immunocytochemical fluorescence staining, the semi-quantification was measured by HPIAS– 100 analysis, and the expression of IL-4 in supernatants were measured by ELISA. The difference of the expression of PI-3K between groups was compared with that of the expression of IL-4.Results:Immunocytochemical fluorescence staining showed that the fluorescence intensity of asthmatic T lymphocyte was significantly higher than that of normal control T lymphocyte, expressing that the expression of PI-3K in T lymphocyte of asthmatic T lymphocyte were significantly higher than that of normal control T lymphocyte(ρ<0.05), and the difference between chronic asthmatic groups and normal control group were much significant(ρ<0.001), even much difference was found between acute and chronic stage asthmatic groups(ρ<0.05), but there was no significant difference was found between asthmatic 2 weeks group and asthmatic 4 weeks group(ρ﹥0.05).IL-4 protain in supernatants of asthmatic T lymphocyte were significantly higher than that of normal control T lymphocyte(ρ<0.05), but there was no significant difference was found between asthmatic groups(ρ﹥0.05).There was good positive correlation between the expression of PI-3K in T lymphocyte and the IL-4 protain in supernatants (r = 0.583 ,ρ< 0.01).Conclusion:PI-3K signal pathway may participated in the processes of activation, development and persistence of asthmatic T lymphocyte, thus may play an important role in the pathogenesis of asthma.